So it would seem that if we want to know how long it was since an organism died, all we have to do is see how racemic its amino acids are. The process of racemization would have to go at a constant rate, and we'd have to know what it was. As a result, it isn't possible to say that racemization happens at such-and-such a rate. Suppose we examine a particular material (let us say tests of the foraminiferan Neogloboquadrina pachyderma) in a particular environment (let us say in mud in Arctic waters) and by comparing it with a dating method we know we can rely on, we establish that under these conditions racemization does happen at a reasonably steady rate.
In that case we could use the foraminiferans to date sediment in places where we aren't able to use radiometric dating.
The method is based on the determination of ratios of D and L amino acid enantiomers in organic matrices of biogenic carbonates.
In this study we use AAR as a tool for dating Holocene barrier islands sediments.
An object is said to have chirality if it is not possible to make it into a mirror-image of itself by turning it round.
pachyderma, having found that racemization rates differed even between different species of forams.
So dating by racemization can have a few applications, but the conditions under which it can confidently be applied are rather rare.
In particular the marine reservoir effect of radiocarbon means that radiocarbon dating cannot be applied to sediments younger than about 400 years.
Amino acid racemization dating (AAR) is a viable alternative for dating young sediments.